The objectives of this project are to determine the metabolites of aflatoxin B1 formed by the rainbow trout. Both in vivo and in vitro systems will be used and the interactions and transformations which occur in microsomal and non-microsomal systems will be investigated. The carcinogenicity and toxicity of identified metabolites will be assayed using the induction of hepatoma in the very sensitive rainbow trout embryo, by animal and fish feeding trials, and by use of the mutagen assay method employing Salmonella typhimurium TA 1538. Certain environmental chemicals which may occur in our food and water markedly effect these biotransformations and the incidence of cancer and tumor yield. Similarly, the type and level of dietary protein has a marked effect on aflatoxin carcinogenesis in trout. We propose to investigate these parameters in detail and correlate these findings with the extent of covalent binding to macromolecules; continue studies on the role of aflatoxicol (AFL) in carcinogenesis and the factors which effect the equilibrium of AFB1 yields AFL. This will be examined in resistant and sensitive species of salmonids and in the trout embryo. Sterigmatocystin, a carcinogenic mold metabolite structurally related to aflatoxin B1, will also be investigated.